Monte B Cowboy
Jul 25, 2012 8:55am
Re: Non-Dead Freakin' hippie
will Alaska’s Bristol Bay region have many of these mines by 2025?
Two mining giants have so far spent about $450 million on exploratory drilling, permit preparations and a public relations campaign to win over the local population. With an estimated 80 billion pounds of copper, Bristol Bay would represent the largest copper mine in North America. If the project is approved, the companies expect to spend an additional $7 billion to develop a mine valued as high as one half trillion dollars.
On its Web site, the mining company has illustrated the extent of the known deposit. It shows more than a half mile deep of high-grade copper ore. It contains an estimated 80 billion pounds of copper, 5.5 billion pounds of molybdenum and 100 million ounces of gold.
The major tradeoff is the potential environmental damage that the proposed Pebble Mine could mean for Bristol Bay, home to the world’s largest sockeye salmon fishery. It’s the largest sockeye salmon-producing system in the world. It’s produced up to 60 million fish returning from a single spawning event. The salmon fishery in Bristol Bay is set in an almost pristine ecosystem, unique in the world. Its waters are fed by a vast network of rivers, lakes and wetlands threaded through the mountains and tundra of southwestern Alaska.
The company says it’s too early to show real plans, but there are preliminary drawings on file with the Securities and Exchange Commission. What they describe is an open pit mine that could become two to three miles wide and a mile deep. It would be one of the largest open-pit mines in the world.
Next to the mine, a tailings dam will rise 700 feet high, covering several square miles and able to hold billions of tons of mining waste. And as mining continues, another tailings dam will be needed.
They would be among the largest man-made structures on earth.
A byproduct of this process is an enormous amount of waste. In the case of Pebble Mine, it’s estimated that the mine could create up to 10 billion tons of waste, which would need to be stored and monitored forever.
It’s hard to imagine what 10 billion tons really is.
If 10 billion tons were in a square column 1,000 feet wide and 1,000 feet high, it would be somewhere between 29 and 30 miles long.
Copper is toxic. At high levels, it simply kills fish. But the typical toxic effects are much more pernicious and much less visible. For example, the fish — they use their sense of smell to locate the stream in which they were spawned, in which they were going to themselves breed before they die. And we know from various research studies that the sense of smell is affected by copper at much lower concentrations than would actually cause the fish to keel over and die.
And so you could put a small concentration of copper in the water. Fish wouldn’t keel over dead, and so you’d say, “Well, there doesn’t seem to be a problem here.” But you’ve made a subtle change in the sensory system, rendering it less able to avoid predators, less able to find prey, less able to home back to the stream.
The minerals that we’re trying to mine are what are called sulfide minerals. The most common sulfide mineral is iron sulfide, pyrite. And what happens when you expose pyrite to oxygen and to water is that it breaks down chemically into a weak sulfuric acid. That acid, in turn, will dissolve some of these other accompanying sulfide minerals that contain lead, zinc, cadmium, selenium, arsenic, and a whole host of other things.
And now you have a problem because you have water with acid in it, as well as metals that are in solution. And those metals in solution can be very damaging. The old name for those waters is acid mine drainage.
The greatest concern is that over time, a toxic plume of these dissolved metals could eventually leach from the tailings dams into nearby rivers and Lake Iliamna.
full story at PBS Frontline